Guidance for External PSK Usage in TLS
draft-ietf-tls-external-psk-guidance-00

Document Type Active Internet-Draft (tls WG)
Last updated 2020-06-19 (latest revision 2020-06-17)
Replaces draft-dt-tls-external-psk-guidance
Stream IETF
Intended RFC status (None)
Formats plain text html pdf htmlized (tools) htmlized bibtex
Stream WG state WG Document
Document shepherd No shepherd assigned
IESG IESG state I-D Exists
Consensus Boilerplate Unknown
Telechat date
Responsible AD (None)
Send notices to (None)
tls                                                           R. Housley
Internet-Draft                                            Vigil Security
Intended status: Informational                                J. Hoyland
Expires: 20 December 2020                                Cloudflare Ltd.
                                                                M. Sethi
                                                                Ericsson
                                                               C.A. Wood
                                                         Cloudflare Ltd.
                                                            18 June 2020

                 Guidance for External PSK Usage in TLS
                draft-ietf-tls-external-psk-guidance-00

Abstract

   This document provides usage guidance for external Pre-Shared Keys
   (PSKs) in TLS.  It lists TLS security properties provided by PSKs
   under certain assumptions and demonstrates how violations of these
   assumptions lead to attacks.  This document also discusses PSK use
   cases, provisioning processes, and TLS stack implementation support
   in the context of these assumptions.  It provides advice for
   applications in various use cases to help meet these assumptions.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Source for this draft and an issue tracker can be found at
   https://github.com/tlswg/external-psk-design-team
   (https://github.com/tlswg/external-psk-design-team).

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 20 December 2020.

Housley, et al.         Expires 20 December 2020                [Page 1]
Internet-Draft   Guidance for External PSK Usage in TLS        June 2020

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.  Code Components
   extracted from this document must include Simplified BSD License text
   as described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions and Definitions . . . . . . . . . . . . . . . . .   3
   3.  Notation  . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  PSK Security Properties . . . . . . . . . . . . . . . . . . .   3
   5.  Privacy Properties  . . . . . . . . . . . . . . . . . . . . .   5
   6.  External PSK Use Cases and Provisioning Processes . . . . . .   5
     6.1.  Provisioning Examples . . . . . . . . . . . . . . . . . .   6
     6.2.  Provisioning Constraints  . . . . . . . . . . . . . . . .   7
   7.  Recommendations for External PSK Usage  . . . . . . . . . . .   7
     7.1.  Stack Interfaces  . . . . . . . . . . . . . . . . . . . .   8
       7.1.1.  PSK Identity Encoding and Comparison  . . . . . . . .   9
       7.1.2.  PSK Identity Collisions . . . . . . . . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  10
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  10
     10.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This document provides usage guidance for external Pre-Shared Keys
   (PSKs) in TLS.  It lists TLS security properties provided by PSKs
   under certain assumptions and demonstrates how violations of these
   assumptions lead to attacks.  This document also discusses PSK use
   cases, provisioning processes, and TLS stack implementation support
   in the context of these assumptions.  It provides advice for
   applications in various use cases to help meet these assumptions.

Show full document text